Answer: Define Active transport
Explanation: The moving of molecules or ions across the cell membrane.
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They are like that because they can't always be faulty and may have at least some spark of truth to this theory also as stated earlier a theory in scientific terms is just an observation so it can't really be turned down hence theory.
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Here is a image. Hope this helps :)
" As we follow along on a cladogram, it will split at nodes into two or more internodes a specitation event (the formation of new species). The line between two specification events, the internode, represents at least one hypothetical ancestor."